The appearance of lipase enzymes suitable for detergent applications gave the formulator a new approach to improve grease removal. Such enzymes catalyse the hydrolysis of triglycerides which form a major component of many commonly encountered fatty soils such as sebum, animal fats (e.g. lard, ghee, butter) and vegetable oils (e.g. olive oil, sunflower oil, peanut oil). However these enzymes typically showed weak performance in the first wash cycle and typically came with a malodor arising, it is believed, from hydrolysis of fats present in dairy soils like milks, cream, butter and yogurt. While not being bound by theory, it is believed that such soils are prone to lipase-induced malodor generation as they contain triglycerides functionalized with short chain (e.g. C4) fatty acyl units which release malodorous volatile fatty acids after lipolysis. Even the when the performance of such enzymes was improved, the malodor issue remained. Thus, the use of this technology was severely limited.
We have found that the combination of a fabric hueing agent with certain lipase variants gives rise to an improved cleaning performance benefit, while minimising unacceptable malodor. Without wishing to be bound by theory, it is believed that the following mechanisms are likely to give rise to such benefits: selected lipase variants increase the level of grease removal thus leading to better accessibility of the fabric hueing agent to the fabric surface and hence, improved deposition. The resulting combination of improved oily soil removal and shading colorant deposition leads to a improvement in fabric appearance; even where oily soil isn't adequately removed, the hydrolysis of fats into more hydrophilic fatty acids, mono- and di-glycerides leads to improved shading colorant deposition and, hence, cleaning perception; and the presence of dye molecules deposited in the oily soils present on fabrics may inhibit enzyme activity that gives rise to malodor.